Planet 9781600442612

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  • ORIGINS OF EARTH Our planet is one of nine planets circling the Sun. Our whole MANTLE solar system is just one of many millions in a vast universe. This section contains more iron than the crust and is like melted plastic the nearer it gets to the core. How old is Earth OUTER CORE This is an incredibly Earth was formed around hot 6,692F (3,700C). 4.7 billion years ago This, plus the inner core, is larger than Dinosaurs arrived around the planet Mars! 250 million years ago INNER CORE Humans arrived around This section is a solid 1 ,000 years ago 1 ball composed mainly of iron. It is the hottest part, Imagine time as represented by the distance at 7,772F (4,300C)! between your outstretched arms. The universe was formed on your longest left-hand finger. One-cell lifeforms began between your wrist and your elbow. Dinosaurs did not appear until you reach your right hand. Humans arrived on the fingernail of your longest right-hand finger! How was Earth formed The latest theory is that Earth formed from a gigantic cloud of spinning gas and dust. Heres what is thought to have happened. THE CRUST A floating cloud Gases formed The remaining The planets This section is thickest of gas and dust inside the dust continued collided and at the Himalayas (43 miles/70 was sent spinning cloud to to spin around were sent kilometers) and thinnest spinning by an form a new the Sun, forming spinning into beneath exploding star. starour Sun. the planets. their orbits. the oceans (3 miles/2
  • Was there life on Earth from the beginning Definitely not! At first, Earths surface was far too hot to support any form of life. Gradually, however, it cooled down so that a thin crust formed round the outside. It remained boiling hot insideand is still the same today! When did life on Earth start The oldest microfossil found so far is 3,500 million years old. Life began about 1,000 million years after Earth was formed. Scientists tend to date the age of rocks to give us clues to Earths age, working on a calendar that spans millions of years. Early life on Earth. What does Earth look like ORIGINS OF EARTH It was Neil Armstrong, the first man to walk on the Moon in July 1969 who said Earth looked , like a splendid jewel suspended in space. That is what it looked like to him from his Apollo spaceship. Seen from space, the beautiful appearance of Earth is caused by sunlight reflecting off the oceans. This gives the planet its special sparkling blue FACT BYTES appearance. Wreaths of cloud The distance round Earth from top to appear as bottom and round swirling white the middle is almost the same40,000 masses, while kilometers (24,860 miles)its slightly land covers only different because about one quarter the world isntEarth is made up of layers. exactly round. of the surface We live on the crust. of Earth. Earth as seen from space. 3
  • THE SUN Our Sun was formed billions of years ago. All the planets in the solar system orbit the Sun, and it provides warmth and light to Earth. Despite being very old, both the surface of the Sun and its interior are hotbeds of activity. How big is the Sun SOLAR FLARE The Sun is truly massive. To give you some idea, it is 1 times wider than Earth and you could fit 10 CORONA Earth into the Sun about 1,300,000 times! Interestingly, the temperature of the Suns surface is about the same as at Earths core. CONVECTIVE ZONE How hot is the Sun RADIATIVE ZONE As you would expect from such a gigantic fireball, the temperature is blazing hot. At the center of the Sun it is estimated to be around 59 million degrees CORE Fahrenheit (15 million degrees Centigrade). Thats hot enough to melt absolutely anything instantly! What is the Sun made of and how does it work The Sun started as a rotating cloud of gas and dust. This rotation flattened the cloud and pressed the dust together in the center so that it became a larger lump. Once enough matter had been pressed together, the lump became larger, very dense (squashed) and very hot! Once the heat reached a certain point, nuclear reactions began and the star, our Sun, was born! The nuclear reactions at the Suns center create enough pressure to prevent the Sun collapsing. FACT BYTES From the earliest times, humans have realized the need for the Sun to sustain life. The Aztecs of ancient Mexico, the Incas of Peru and the ancient Egyptians all worshipped the Sun as The Sun started as a After the Sun was Earth relies on the Suns a god. cloud of dust and gas formed, dust around it heat and light to sustain and formed a large ball. clumped together, life on its surface.4
  • What is the difference between a sun and a star